Presentation: "Periodic table of D.I. Mendeleev. Structure of the atom"

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He is one of the most brilliant chemists of the 19th century; carried out numerous determinations of the physical constants of compounds (specific volumes, expansion, etc.), studied the Donetsk coal deposits, and developed the theory of solutions. He wrote “Fundamentals of Chemistry” (1868-1871), a work whose numerous editions influenced inorganic chemists. M. Jua Dmitry Ivanovich Mendeleev

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Dmitry Ivanovich Mendeleev D.I. Mendeleev is the author of fundamental research in chemistry, physics, metrology, meteorology, economics, fundamental works on aeronautics, agriculture, chemical technology, public education and other works closely related to the needs of the development of the productive forces of Russia.

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Dmitry Ivanovich Mendeleev was born on February 8, 1834 in the village of Verkhnie Aremzyany near Tobolsk, in the family of a gymnasium director and a school trustee. He was the fourteenth child in the family. He was raised by his mother, since the father of the future chemist died shortly after his birth. Dmitri Ivanovich Mendeleev

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Scientific activity D.I. Mendeleev studied (in 1854-1856) the phenomena of isomorphism, revealing the relationship between the crystalline form and chemical composition of compounds, as well as the dependence of the properties of elements on the size of their atomic volumes. He discovered the “absolute boiling point of liquids,” or critical temperature, in 1860. On December 16, 1860, he writes from Heidelberg to the trustee of the St. Petersburg educational district I.D. Delyanov: “... the main subject of my studies is physical chemistry.” D.I. Mendeleev is the author of the first Russian textbook “Organic Chemistry” (1861).

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The periodic table of chemical elements is a classification of chemical elements that establishes the dependence of various properties of elements on the charge of the atomic nucleus. The system is a graphic expression of the periodic law established by the Russian chemist D. I. Mendeleev in 1869. Its original version was developed by D.I. Mendeleev in 1869-1871 and established the dependence of the properties of elements on their atomic weight (in modern terms, on atomic mass). In total, several hundred options for depicting the periodic table have been proposed. In the modern version of the system, it is assumed that the elements are summarized in a two-dimensional table, in which each column (group) defines the main physical and chemical properties, and the rows represent periods that are to a certain extent similar to each other.

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The periodic system of chemical elements (periodic table) is a classification of chemical elements that establishes the dependence of various properties of elements on the charge of the atomic nucleus. The system is a graphic expression of the periodic law established by the Russian chemist D. I. Mendeleev in 1869.

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Structure of the periodic table

The most common are 3 forms of the periodic table: “short” (short-period), “long” (long-period) and “extra-long”. In the “super-long” version, each period occupies exactly one line. In the “long” version, lanthanides and actinides are removed from the general table, making it more compact. In the “short” form of recording, in addition to this, the fourth and subsequent periods occupy 2 lines each; The symbols of the elements of the main and secondary subgroups are aligned relative to different edges of the cells.

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"SHORT" PERIODAL TABLE

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LONG FORM OF THE PERIODAL TABLE

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The short form of the table containing eight groups of elements[was officially abolished by IUPAC in 1989. Despite the recommendation to use the long form, the short form continues to be given in a large number of Russian reference books and manuals even after this time. From modern foreign literature, the short form is completely excluded, and the long form is used instead. Some researchers attribute this situation, among other things, to the apparent rational compactness of the short form of the table, as well as to inertia, stereotypical thinking and non-perception of modern (international) information.

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The significance of the periodic system D. I. Mendeleev’s periodic system became a major milestone in the development of atomic-molecular science. Thanks to her, the modern concept of a chemical element was formed, and ideas about simple substances and compounds were clarified. Mg (magnesium): 12 – chemical number. Element in Mendeleev's PSHE (corresponds to the number of protons and electrons); 2 - number of electrons at the first energy level; 8 – at 2nd energy level; 2 – number of electrons at 3rd energy level; 24, 312 – atomic mass of the chemical element.

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Developed in the 19th century. within the science of chemistry, the periodic table was a ready-made systematization of the types of atoms for new branches of physics that developed at the beginning of the 20th century. - atomic physics and nuclear physics. In the course of studying the atom using physics methods, it was found that the serial number of an element in the periodic table (atomic number) is a measure of the electric charge of the atomic nucleus of this element, the number of the horizontal row (period) in the table determines the number of electron shells of the atom, and the number of the vertical row determines the quantum structure the upper shell, to which the elements of this series owe the similarity of chemical properties.

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The appearance of the periodic system opened a new, truly scientific era in the history of chemistry and a number of related sciences - instead of scattered information about elements and compounds, a coherent system appeared, on the basis of which it became possible to generalize, draw conclusions, and predict.

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Definitions that we need to know to study the topic:

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An atom is an electrically neutral system of interacting elementary particles, consisting of a nucleus (formed by protons and neutrons) and electrons.

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Atomic structure model

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Isotopes are varieties of atoms of the same chemical element that have the same number of protons but a different number of neutrons. + 1H - protium (H)

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2H - deuterium (D)

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3H - tritium (radioactive) (T).

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A chemical element is a type of atom with the same positive nuclear charge.

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An electron cloud is the space around an atomic nucleus in which an electron is most likely to be found.

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Shapes of electron clouds.

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Orbitals, or sublevels, as they are also called, can have different shapes, and their number corresponds to the level number, but does not exceed four. The first energy level has one sublevel (s), the second has two (s,p), the third has three (s,p,d), etc. Electrons of different sublevels of the same level have different shapes of the electron cloud: spherical (s), dumbbell-shaped (p) and more complex configurations (d) and (f). Scientists have agreed to call a spherical atomic orbital an s-orbital. It is the most stable and is located quite close to the core.

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S-level form.

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P-sublevel form.

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Formd-sublevel.

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The electron shell is the totality of all electrons in an atom.

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Electrons with similar energies form a single electron layer. + Z K L M N O P Q 1 2 3 4 5 6 7

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The periodic system of D.I. Mendeleev in the light of the doctrine of the structure of the atom.

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Within the same period, metallic properties weaken, and non-metallic properties increase, since: a) the charges of the atomic nuclei of elements increase; b) the number of electrons at the outer energy level of atoms increases; c) the number of energy levels in the atoms of elements does not change; d) the radius of atoms decreases.

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Charge of a hydrogen atom Charge of a lithium atom (both elements are located in the first period)

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Within the same group (in the main subgroup), metallic properties increase, and non-metallic properties weaken, since: a) the charges of the atomic nuclei of elements increase; b) the number of electrons at the external energy level does not change; c) the number of energy levels in atoms increases; d) the radius of the atoms increases.

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Charge of a carbon atom

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Charge of a nitrogen atom

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Examples of Graphic Formulas of Some Metals and Non-Metals

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Elements of non-metals Non-metals are chemical elements with typically non-metallic properties that occupy the upper right corner of the Periodic Table. Their location in the main subgroups of the corresponding periods is as follows: In addition, hydrogen and helium are also classified as nonmetals. A characteristic feature of nonmetals is a larger (compared to metals) number of electrons in the outer energy level of their atoms. This determines their greater ability to attach additional electrons and exhibit higher oxidative activity than metals. Nonmetals have high electron affinities, high electronegativity, and high redox potential.

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N 5 2 2 Brief electronic configuration 2s2p 2 3

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F 2 7 Brief electron configuration 2s2p 2 5

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As 2 5 18 8 Brief electron configuration 4s4p 2 3

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I 2 18 18 8 7 Brief electronic configuration 5s5p 2 5

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Prerequisites for the discovery of the Periodic Law

• Berzelius classification
• Döbereiner's triads
• Helix-axis of the Chancourtois screw
• Newlands Octaves
• Meyer tables

Dmitry Ivanovich Mendeleev was born on February 8, 1834 in Tobolsk, in the family of the director of the gymnasium, Ivan Pavlovich Mendeleev, and was the last, seventeenth child.

He was the closest adviser to the Chairman of the Cabinet of Ministers, Sergei Witte, who actually directed Russia along the path of state capitalism. And Mendeleev greatly contributed to this development.

Mendeleev was the ideologist of the oil industry in our country. His phrase “drowning with oil is like burning banknotes” became an aphorism. He understood the importance of petrochemicals and convinced Witte to build the first petrochemical plant in Russia

S. Witte

D. I. Mendeleev entered into a conflict with the Nobel brothers, which lasted throughout the 1880s. Ludwig Nobel, taking advantage of the crisis in the oil industry, and striving for a monopoly on Baku oil, on its production and distillation, for this purpose speculated on rumors about its depletion .

L. Nobel

Discovery of the Periodic Law by D.I. Mendeleev

• Classification of chemical elements according to characteristics: atomic mass and properties of substances formed by chemical elements.
• I wrote down on cards all the known information about the discovered and studied chemical elements and their compounds and compiled natural groups of elements with similar properties.
• Discovered that the properties of elements within certain limits change linearly (monotonically increase or decrease), then after a sharp jump repeat periodically , i.e. After a certain number of elements, similar ones occur.

First version of the periodic table

Based on his observations on March 1, 1869, D.I. Mendeleev formulated the periodic law, which in its initial formulation sounded like this: the properties of simple bodies, as well as the forms and properties of compounds of elements, are periodically dependent on the values ​​of the atomic weights of the elements

Periodic table

DI. Mendeleev

The weak point of the periodic law immediately after its discovery was the explanation of the reason for the periodic repetition of the properties of elements with an increase in the relative atomic mass of their atoms. Moreover, several pairs of elements are arranged in the Periodic Table with a violation of the increase in atomic mass. For example, argon with a relative atomic mass of 39.948 ranks 18th, and potassium with a relative atomic mass of 39.102 has an atomic number of 19.

Periodic law

DI. Mendeleev

Only with the discovery of the structure of the atomic nucleus and the establishment of the physical meaning of the atomic number of an element, it became clear that in the Periodic Table there are located in order of increasing positive charge of their atomic nuclei. From this point of view, there is no disturbance in the sequence of elements 18 Ar – 19 K, 27 Co – 28 Ni, 52 Te – 53 I, 90 Th – 91 Pa. Hence, modern interpretation of the Periodic Law sounds like this:

The properties of chemical elements and the compounds they form periodically depend on the charge of their atomic nuclei.

Periodic table

chemical elements

Periods are horizontal rows of chemical elements, 7 periods in total. The periods are divided into small (I, II, III) and large (IV, V, VI), VII - unfinished.

Each period (except for the first) begins with a typical metal (Li, Na, K, Rb, Cs, Fr) and ends with a noble gas (He, Ne, Ar, Kr, Xe, Rn), which is preceded by a typical non-metal.

Periodic table

chemical elements

Groups are vertical columns of elements with the same number of electrons in the outer electronic level, equal to the group number.

There are main (A) and secondary subgroups (B).

The main subgroups consist of elements of small and large periods. Side subgroups consist of elements of only large periods.

Redox

properties

Change in the radius of an atom in a period

The radius of an atom decreases with increasing charges of atomic nuclei in a period, because the attraction of the electron shells by the nucleus increases. At the beginning of the period there are elements with a small number of electrons in the outer electron layer and a large atomic radius. Electrons located further from the nucleus are easily separated from it, which is typical for metal elements

Changing the radius of an atom in a group

In the same group, as the period number increases, the atomic radii increase. Metal atoms give up electrons relatively easily and cannot add them to complete their outer electron layer.

• In the Middle Ages, scientists already knew ten chemical elements - seven metals (gold, silver, copper, iron, tin, lead, and mercury) and three non-metal (sulfur, carbon, and antimony).

Designation of chemical elements by alchemists

Alchemists believed that chemical elements were associated with the stars and planets, and assigned astrological symbols to them.

Gold was called the Sun, and was designated by a circle with a dot:

Copper is Venus, the symbol of this metal was the “Venus mirror”:

And iron is Mars; As befits the god of war, the designation of this metal included a shield and a spear:

• Associated with the myths of the ancient Greeks - Tantalus and Promethium.

Promethium

In honor of the hero of the ancient myth Prometheus, who gave people fire and was doomed to terrible torment for this (an eagle flew to him, chained to a rock, and pecked at his liver), chemical element No. 61 promethium is named

Geographical origin

• Germanium Ge
• Galium Ga
• France Fr
• Ruthenium Ru
• Polonium Po
• Americium Am
• Europium Eu

In honor of scientists

• Curium Cm
• Fermium Fm
• Mendelevium Md
• Einstein Es
• Lawrence Lr

Names indicating the properties of simple substances

• Hydrogen (H) - giving birth to water
• Oxygen (O) – acid-producing
• Phosphorus (P) – carrier of light
• Fluorine (F) - destructive
• Bromine (Br) – smelly
• Iodine (I) - violet

• Mess in my head
• Not even a kick
• Bright head

The periodic table of chemical elements was discovered by the great Russian scientist Dmitri Mendeleev in March 1869 and finally formulated in the years.

MENDELEEV, Dmitry Ivanovich January 27 (February 8), 1834 - January 20 (February 2), 1907 Russian chemist Dmitry Ivanovich Mendeleev was born in Tobolsk in the family of a gymnasium director. Dmitry was the last, seventeenth child in the family. Of the seventeen children, eight died in infancy. While studying at the gymnasium, Mendeleev had very mediocre grades, especially in Latin.

In 1850, he entered the department of natural sciences of the physics and mathematics faculty of the Main Pedagogical Institute in St. Petersburg. In 1850, he entered the department of natural sciences of the physics and mathematics faculty of the Main Pedagogical Institute in St. Petersburg. In 1855, Mendeleev graduated from the institute with a gold medal and was appointed senior teacher at a gymnasium in Simferopol, but due to the outbreak of the Crimean War, he transferred to Odessa, where he worked as a teacher at the Richelieu Lyceum. In Mendeleev was on a scientific trip to Germany. In Mendeleev was on a scientific trip to Germany.

Upon his return, Mendeleev wrote Organic Chemistry, the first Russian textbook on this discipline, which was awarded the Demidov Prize. One of Mendeleev’s important discoveries dates back to this period - the determination of the “absolute boiling point of liquids,” now known as the critical temperature. He wrote the classic work "Fundamentals of Chemistry". In the preface to the second edition of the first part of the textbook, Mendeleev gave a table of elements entitled “Experience of a system of elements based on their atomic weight and chemical similarity”

In 1860, Mendeleev, together with other Russian chemists, took part in the International Congress of Chemists, at which S. Cannizzaro presented his interpretation of the molecular theory of A. Avogadro. This speech and discussion regarding the distinction between the concepts of atom, molecule and equivalent served as an important prerequisite for the discovery of the periodic law. In 1869, Mendeleev published his diagram of the periodic table in the Journal of the Russian Chemical Society and sent notice of the discovery to the world's leading scientists. Subsequently, the chemist repeatedly refined and improved the scheme until it acquired its usual appearance. The essence of Mendeleev's discovery is that with increasing atomic mass, the chemical properties of elements change not monotonically, but periodically.

One of the legends says that Mendeleev discovered the table of chemical elements in a dream. However, Mendeleev only laughed at the critics. “I’ve been thinking about it for maybe twenty years, and you say: I sat and suddenly... it’s done!” the scientist once said about his discovery.

Another legend credits Mendeleev with the discovery of vodka. In 1865, the great scientist defended his dissertation on the topic “Discourse on the combination of alcohol with water,” and this immediately gave rise to a new legend. The chemist’s contemporaries chuckled, saying that the scientist “creates quite well under the influence of alcohol combined with water,” and subsequent generations already called Mendeleev the discoverer of vodka.

Contemporaries also made fun of Mendeleev’s passion for suitcases. During the period of his involuntary inactivity in Simferopol, the scientist was forced to while away the time by weaving suitcases. Later, he independently made cardboard containers for the laboratory’s needs. Despite the clearly “amateur” nature of this hobby, Mendeleev was often called a “master of suitcases.”

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LAST ELEMENTS OF THE PERIODIC SYSTEM OF CHEMICAL ELEMENTS D.I.MENDELEEVA Chemistry

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Element of the periodic system of Mendeleev No. 110-Darmstadtium Darmstadtium (lat. Darmstadtium, designation Ds; formerly Ununnilium) is an artificially synthesized chemical element of group VIII of the periodic system, atomic number 110. Atomic mass = 281 (g/mol) History. The element was named after its discovery site. First synthesized on November 9, 1994 at the Center for Heavy Ion Research, Darmstadt, by S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Münzenberg, H. Schott and others. The discovered isotope had an atomic mass of 269. Preparation Darmstadtium isotopes were obtained as a result of nuclear reactions: Properties Radioactive.

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Element of the periodic system of Mendeleev No. 111 - Roentgenium Roentgenium (Latin Roentgenium, designation Rg; formerly unununium) is an artificially synthesized chemical element of the side subgroup of the first group, the seventh period of the periodic system, with atomic number 111. The simple substance roentgenium is a transition metal. Atomic mass 280 (g/mol) History Element 111 was first synthesized on December 8, 1994 in the German city of Darmstadt. The authors of the first publication were S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Münzenberg, H. Schött, A. G. Popeko, A. V. Eremin, A. N Andreev, S. Saro, R. Janik, and M. Leino. In addition to the German physicists, the international team included three scientists from the Russian Joint Institute for Nuclear Research. The first synthesis was carried out according to the reaction: 209Bi + 64Ni = 272Rg + n

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Element of the periodic table of Mendeleev No. 112 - Copernicium Copernicium (Latin Copernicium, Cn; Copernicus is also used as the Russian name) is the 112th chemical element. The nucleus of its most stable known isotope, 285Cn, consists of 112 protons, 173 neutrons and has a half-life of about 34 seconds. Belongs to the same chemical group as zinc, cadmium and mercury. History Copernicium was first synthesized on February 9, 1996 at the Heavy Ion Institute in Darmstadt, by S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster ), H. Folger, G. Münzenberg and others. Name GSI scientists proposed the name Copernicium (Cn) for element 112 in honor of Nicolaus Copernicus. On February 19, 2010, Copernicus's birthday, IUPAC officially approved the name of the element. Previously, the names proposed for it were Strassmannium St, Venusium Vs, Frischian Fs, Heisenbergium Hb, as well as Laurentium Lv, Wyxhouseium Wi, Helmholtzium Hh.

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Element of the periodic system of Mendeleev No. 113 - Ununtrium Ununtrium (lat. Ununtrium, Uut) or eka-thallium - the 113th chemical element of group III of the periodic system, atomic number 113, atomic mass, the most stable isotope 284Uut. History of the discovery In February 2004, the results of experiments carried out from July 14 to August 10, 2003 were published, as a result of which the 113th element was obtained. The research was carried out at the Joint Institute for Nuclear Research (Dubna, Russia). Preparation Ununpentium isotopes were obtained as a result of the α-decay of ununpentium isotopes: as well as as a result of nuclear reactions:

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Element of the periodic system of Mendeleev No. 114 - Ununquadium Ununquadium, the officially proposed name is flerovium (Latin Flerovium, Fl) - the 114th chemical element of group IV of the periodic system, atomic number 114. The element is radioactive. History The element was first obtained in December 1998 by isotope synthesis through the fusion reaction of calcium nuclei with plutonium nuclei. Origin of the name Officially proposed, but not approved, the name flerovium or flerovium is given in honor of the Russian physicist G. N. Flerov, the leader of the group that synthesized elements with numbers from 102 to 110. After approval procedures between Russian and American scientists, on December 1, 2011, the commission on A proposal was sent to the IUPAC nomenclature of chemical compounds to name the 114th element florovium. Chemical properties Some studies have indicated that ununquadium has chemical properties not similar to lead, but to noble gases. Ununquadium is presumably capable of exhibiting the +2 and +4 oxidation states in compounds, although since the stability of the +4 oxidation state decreases with increasing atomic number, some scientists suggest that ununquadium will not be able to exhibit it or will only be able to exhibit it under harsh conditions.

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Element of the periodic system of Mendeleev No. 115 - Ununpentium Ununpentium (lat. Ununpentium, Uup) or eka-bismuth - the 115th chemical element of group V of the periodic system, atomic number 115, atomic mass 288, the most stable nuclide. An artificially synthesized element, not found in nature. History of the discovery In February 2004, the results of experiments carried out from July 14 to August 10, 2003 were published, as a result of which the 115th element was obtained. The research was carried out at the Joint Institute for Nuclear Research (Dubna, Russia). Preparation Isotopes of ununpentium were obtained as a result of nuclear reactions:

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Element of the periodic system of Mendeleev No. 116 - Unungexium Unungexium (Latin Ununhexium, Uuh), the officially proposed name is Livermorium (Latin Livermorium, Lv) - the 116th chemical element of group VI of the periodic system, atomic number 116, atomic mass 293. Discovery history Statement about the discovery of elements 116 and 118 in 1999 in Berkeley (USA)[ turned out to be erroneous and even falsified. Synthesis according to the announced method was not confirmed in the Russian, German and Japanese nuclear research centers, and then in the United States itself. Unungexium was discovered by synthesis of isotopes in 2000 at the Joint Institute for Nuclear Research (Dubna, Russia). Name Officially proposed, but not approved, the name Livermorium is given in honor of the city of Livermore (California), where the Livermore National Laboratory is located. JINR scientists proposed the name moscovium for the 116th element - in honor of the Moscow region. Preparation Isotopes of unungexium were obtained as a result of nuclear reactions:

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Element of the periodic table of Mendeleev No. 117 - Ununseptium Ununseptium (lat. Ununseptium, Uus) or eka-astatine is a temporary name for the chemical element with atomic number 117. Temporary designation is Uus. Half-life - 78 milliseconds. Halogen. Receipt Was obtained at the Joint Institute for Nuclear Research in Dubna, Russia in 2009-2010. To synthesize the element, the following reactions were used: Origin of the name The word “ununseptium” is formed from the roots of Latin numerals and literally means something like “one-one-seven” (the numeral “117th” is constructed completely differently). The name will be changed in the future.

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Element of the periodic table of Mendeleev No. 118 - Ununoctium Ununoctium (Latin Ununoctium, Uuo) or eka-radon is a temporary name for the chemical element with atomic number 118, the synthesis of isotopes of which was first carried out in 2002 and 2005 at the Joint Institute for Nuclear Research (Dubna) in collaboration with Livermore National Laboratory. The results of these experiments were published in 2006. Temporary designation - Uuo. The element is the heaviest non-metal that can exist and is probably classified as a noble gas. History of discovery The statement about the discovery of elements 116 and 118 in 1999 in Berkeley (USA) turned out to be erroneous and even falsified. Synthesis according to the announced method was not confirmed in the Russian, German and Japanese nuclear research centers, and then in the USA. The first event of the decay of element 118 was observed in an experiment conducted at JINR in February - June 2002. Preparation Ununoctium was obtained as a result of a nuclear reaction:

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Interesting facts: Elements numbered 110, 111 and 112 were discovered by German scientists back in the 1990s. Previously, they were given the unpronounceable names of ununnilii, ununinii and unubii. On Friday, IUPAC approved new names for these artificially synthesized elements - darmstadtium, roentgenium and copernicium. The official symbols of elements in the periodic table are Ds, Rg and Cn. The names of the 114th and 116th elements have not yet been approved. In nature, there are no elements with atomic numbers (the number of protons in the nucleus of an atom) greater than 92, that is, heavier than uranium. Heavier elements, such as plutonium, can be produced in nuclear reactors, and elements heavier than 100th (fermium) can only be produced in accelerators, by bombarding a target with heavy ions. When the nuclei of the target and the “projectile” merge, the nuclei of a new element appear. Where is the end of the table? Academician Oganesyan, in an article published in the journal Pure and Applied Chemistry, writes that the theory of quantum electrodynamics and the theory of the atom created by Rutherford allows for the existence of atoms with the number of protons in the nucleus equal to 170 or even more. That is, theoretically, the periodic table can continue until the 170th cell.

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Prerequisites for creating the table Prerequisites for creating the table The greatest contribution that changed the entire course of science was the idea of ​​​​the brilliant Russian scientist Dmitry Ivanovich Mendeleev, who set himself the goal of understanding the whole variety of chemical elements and bringing them into a single system. How was the problem posed by Mendeleev solved? “Having devoted my energies to the study of matter, I see in it two such signs or properties: mass, occupying space and manifested in weight, and individuality, expressed in chemical transformations.” From here, continued D.I. Mendeleev, “... the thought involuntarily arises that there must be a connection between mass and chemical elements, and since the mass of a substance, although not absolute, but only relative, is finally expressed in the form of atoms, then it is necessary to look for correspondence between individual properties elements and their atomic weights." Thus, in the infinite variety of properties inherent in various substances, Mendeleev saw that common property, which, being inherent in all chemical elements, led him to the discovery of the greatest law of nature, which became the guiding law not only for chemists and physicists, but also for any specialists involved in the study of matter . Thus, a property inherent in all substances turned out to be the weight of their constituent atoms - atomic weight.

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In March 1869 Mendeleev informed the Russian Chemical Society about the law he discovered in the article “Relationship of properties with the atomic weight of elements” and at the same time formulated the main provisions of the open law. Using the law, Mendeleev predicted and described in detail the properties of some still unknown elements. Further discoveries of chemical elements confirmed the correctness of Mendeleev's predictions and placed Mendeleev's name in first place in the history of not only chemistry, but also all natural science. In total, Mendeleev predicted the existence of eleven chemical elements, including polonium, radium, and protactinium. In March 1869 Mendeleev informed the Russian Chemical Society about the law he discovered in the article “Relationship of properties with the atomic weight of elements” and at the same time formulated the main provisions of the open law. Using the law, Mendeleev predicted and described in detail the properties of some still unknown elements. Further discoveries of chemical elements confirmed the correctness of Mendeleev's predictions and placed Mendeleev's name in first place in the history of not only chemistry, but also all natural science. In total, Mendeleev predicted the existence of eleven chemical elements, including polonium, radium, and protactinium.